Technical Questions - Cooling System
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Page last updated 9 December, 2009





Date asked

Question Answer

9th December 2009


...Did you ever hear of a 10 Blade fan from Kenlow part #'s supposed to be black..

The 10 blade fan was fitted from chassis number 3268, a 6 blade type was fitted before this. To be honest the original fan was pretty poxy and the bracket meant it wasn't really very good for airflow. You would be better going for a new style kenlowe or pacet type fan. Various people have written articles about this and the various mod's that can be made, including multiple fans, push or pull type, radiator ducting, spare wheel removal, radiator replacement etc. The short wide radiator can be made to perform well however simply by fitting a couple of small modern fans and adding a special additive called water wetter which drops the coolant temp by a few degrees - by reducing the surface tension (and therefore cavitation) of the coolant.

13th April 2008

By Farrah Day

I haven't seen this mentioned on the TVR forum, so thought I'd share something that we've learned in case it can help others. (I can't post there as I'm not a member).

A puzzle then that we finally solved and that might well apply to some TVR owners and other Essex engined vehicle owners.

You might remember from past emails that we replaced the Essex engine in our Land Rover over Christmas, as the old one had worn piston rings and lacked power. Well all was fine with the replacement engine, ran nice and much more powerful, but we soon realised that it appeared (as did the old one) to be running extremely hot. In fact the needle on the temp gauge was wrong side of the red and trying relentlessly to escape the casing! At first we thought it might be due to the fan on the Essex being slightly offset from the radiator and so not pulling enough air through, or the viscous coupling was knackered. However given that the Land Rover radiator is big and known for its over-cooling, we then suspected that the radiator itself might be blocked.

We had changed the thermostat in case this was faulty, and suspected also that maybe the water pump propellor had perished. Thermostat was fine, you could feel when it opened and the hot water was passed through the top hose. Without a fan on, we could also feel the hot water being drawn down the radiator and through the bottom hose, eliminating the water pump. With the fan back on, we could feel the hot water going into the top of the radiator, and cold now being drawn through the bottom hose, so radiator was not blocked and working fine. Nothing seemed faulty and although the engine had never actually physically overheated, venting through the rad cap, the temp gauge was still bending past the red.

Eventually we swapped the water temp sender for another Essex one and... no change. We were totally puzzled and out of ideas.

Finally, we decided to swap the water temp sender for a Land Rover unit, but unfortunately it was the wrong fitting. However, as luck had it, we found an adaptor which fitted both the Land Rover sender and the Essex manifold and... BINGO! Problem finally sorted.

All this time we had thought the engine was over heating, it was fine. A simple mismatch between the thermoelectric properties of the Essex water temp sender and the Land Rover water temperature gauge was all it was... and to think of all the times we actually stopped to let the engine cool down for fear of damaging it! What a bugger!

The water temp gauge now sits midway between the blue and the red just as it does with the standard Land Rover engine fitted... at last, such relief!

We've now since fitted an electric fan so that we can make things a little more efficient still.

Just thought it was worth bringing to your attention to this as there are maybe TVR owners out there suffering similar problems and pulling their hair out due to a simple component mismatch.
Thanks for your contribution, Farrah.

2nd May 2007

By Paul Vermeulen

It is with keen interest that I browse your website for technical information, not about the TVR as a whole, but for the Essex V6 engine. In South Africa, it has been very popular to install the engine into the Volkswagen Microbus – primarily for towing boats and caravans etc., where the earlier 2.0 and 2.1 litre VW engines were not powerful enough. I have such a vehicle, and admittedly, it has been quite an exercise in auto engineering.

One common theme on these conversions however, has been the overheating issue. There are several things that can be done – better / bigger radiator fitment, as well as creating ducts with fans for creating airflow over the engine, as being at the rear of the vehicle, far less natural air flows over the engine without this kind of arrangement. The exhaust arrangement is also a critical issue, as the one side pipe runs directly under the sump and some heat shield material is required on the sump to prevent creating an oil cooker at the bottom of the engine.

I have managed to get sufficient cooling to keep the engine in the 82 to 95 degree range (instrument is a VDO electric temperature gauge – capillary is not practical as the distance between engine and instrument panel is almost 4 metres). An 82 degree thermostat is fitted on the engine. The radiator fan up front is controlled by a regular radiator temperature sensor, 65 degree type and there is a manual fan switch fitted in case the sensor fails.

My question is – what is the optimum or design temperature range of the 3 litre V6 Essex engine? Theory suggests that the engine should reach its operating temperature as quickly as possible to reduce wear and reach optimum fuel efficiency. Is it the 82 degrees of the thermostat opening, or is it higher? The reason I ask is that I want to automate the switching on of the radiator fan and the cooling duct fans based on the engine temperature itself, and don’t know what the optimum temperature is.

From an article in a good reference book I use, for best fuel economy the engine coolant temperature is said to be to be around 100ºC to 105ºC (212ºF to 220ºF) on most engines. This is possible using a pressurised system of course...and on new vehicles such as Renaults the cooling fan cuts in at 98ºC - therefore even they allow the engine to get pretty warm before the cooling fan spins. Just make sure if you run hotter that the system is in A1 condition i.e. hoses not perished or old, water pump not seeping coolant from spindle leak hole, radiator not about to go etc etc. Airflow around engine is also important as you've mentioned, and intake air needs to be from a fresh air position.

Oil temperature needs to be 110ºC to115ºC (230ºF to 240ºF) and synthetic oil is recommended due to friction qualities and longer life between changes, however normal oil is fine if changed regularly.

24th July 2005

By Paul Bennett

I need to replace the heater hoses, but I am not sure what diameter bore hose was originally fitted as the hose from the heater outlets needs to be 5/8" (15mm) and the hoses for the heater valve and water pipe to water pump seem to be 1/2" (13mm).

Do you know what size was originally fitted ?.

I have stripped the front end and am in the process of repainting the chassis etc., the bottom of the radiator is located by 2 posts, with rubber grommets and penny washers, split pins.

Do you know if the washers should be fitted between radiator and chassis or from underneath and kept in place with split pins ?.

I also have a query on a pipe connected to the carb that has been blocked @ one end as it is not connected to anything (see photo)

Do you know where this pipe should be connected to ?
I will get back to you on the hose as I need to do some investigating. The radiator washers should go under the grommet and the split pin keeps them in place.

The pipe on the carb could be for the original air filter bypass flap which was vacuum controlled. This can be blanked off if not required.

21st July 2005

By Stefan Gurszky

I fight overheating. The car is equipped with an (new) oil cooler in front of a new radiator (small type) as well as two Pacet fans (in the back of the radiator, pulling air). If there was a fan in front of the radiator, it's gone. The car was serviced by Exactly TVR, so I do have the modification (pipe from reservoire to radiator).
I have no problems as long as I drive, but in town, standing and in stop and go traffic I'm close to get booling water, even with the fans switched on. Now I removed the spare wheel and will check over the weekend if this changes things. I read about some isolation for the manifolds and turbo casing. Do you think ist worth while and might this heat up the turbo too much? Or any other idea?

Follow up on 22nd July:

Overheating: I had a closer look to my fan-setup - strange! Both fans are mounted behind the rad., right one is pulling, left one is pushing - have you ever seen such a layout? As the connector for the fans is under the spare wheel heat sheet, I'll change the connector for the left hand fan over the weekend. This should make it pulling as well and have a look at it's performance. I don't know yet if there is a pulling or pushing blade.
Gauge is recetech and should be capillary.

Follow up on 2nd August 2005:

just to give you an update of my overheating issue:
- put fan in reverse
- taightend belt ot water pump (was a bit loose)

This makes things better, now with the fans on I can held 95-100 deg. standing still in stop and go traffic.

Now the mystery: Putting the interior heating system on takes down up to 10deg with the interior heater blower in second stage. And it is quite hot at the outlets!
This makes me wonder: Compared to the main radiator, this heat exchanger is small but 'cooles' down a lot. Probably lots of the water is pumped through the carb heating and back and not routed via the main water flow and radiator.

The overheating problem could be due to the Turbo, as you have all the other mod's on the car already. However first check your temperature gauge is reading correct. Do you have a capillary (mechanical) gauge or electric? If electric they are pretty vague and you should change over to a capillary type. See other technical questions for ideas. If you already have a capillary gauge fitted then you will need to check for air locks, correct pipe routing (see again Technical Questions), radiator fin damage, water pump internal corrosion, thermostat problems. Please let me know what you find.




Reply on 25th July 2005:

The fan in reverse should then pull not push. I think the previous owner made a mistake there! I do know a pull fan blade is diferent to a push one though - in reverse the fan is not as efficient as using a fan blade to change the direction.

A capillary gauge has a thick tube going to the colling system, an electric gauge has an electrical wire. Think of the capillary gauge like a mercury thermometer - the mercury in the tube expands/contracts and therefore a temperature change is seen. The liquid in the capillary tube alters the dial mechanically so is calibrated and more accurate than an electrical unit. Voltage fluctuations can alter the temp reading on an electrical gauge and also calibration is more vague.

Reply on 3rd August 2005:

I used to cool my old Mini by turning on the heater in the summer - but had to open the windows as it was so hot. This allows many Mini owners prevent overheating until they fit a larger core radiator.

I am guessing that the water flowing through the heater matrix is faster due to the smaller diameter pipes. However the large bore main pipes to the radiator should be flowing at an adequate rate, just that perhaps the Radiator isn't working well enough. It is definately worth changing the thermostat though if you suspect there is a fault with it.

14th July 2005

By Stephen Thackray

I've read with interest Christian's log. I would like to fit the capillary sender unit/gauge this weekend.
Which Smith's model is best suited in your view?

Not too difficult to find are the original looking Smiths water temp gauge to match the original one here, but it's an electric gauge not capillary:

However, not matching the other dials but much more accurate is this capillary one, at least it's still a Smith's gauge:

You may need an adaptor to allow fitment to your engine. Try Demon Tweeks as they do a special sleeve that can fit into a normal water pipe with a take-off for a capillary gauge sender unit - see here:


For Demon Tweeks' gauges try here:


11th July 2005

By Christian Diaz

To get better cooling on my 3000 s, I ordered recently a 16' Kenlowe blower
with thermostatic control.

Once the radiator and engine have been unbolted and removed, I discovered
the 'bulb' on the pulley on which the fan was bolted is... Part of the
pulley. So I have a clearance trouble : i need about 15 cm to replace the
engine fan by the kenlowe unit, but with 'bulb' in place, I only get 10 cm.
Of course, the chassis cross member in front of the rad won't move either!

Any solution for me?

Is it possible to fit another pulley (an "unbulbed one') than the original
one? Where could it be sourced?

How about the metallic bar coming from the engine through the pulley?

Wish the simplest would be to fit the kenlowe in front of the red, even if
the chassis member is between them. Would you agree?

Thanks again for your help! Weather gets so hot here...

It will not be simple to remove or machine down the original fan shaft if
you wish to use it again in the future. Better to fit the fan in front of
the radiator, and then make up a suitable fan duct using sheet aluminium or
plastic to make sure the airflow from the fan (and from driving at speed)
through the radiator and not around the sides.

29th June 2005

By John Wheatcroft

Please can I have a diagram of how the cooling system goes together. I think mine is wrong.

i.e from the tubular header tank, expansion tank, radiator in and out etc etc etc

you know what I mean

Here is the diagram, although as you will see there are a couple of pipes which can confuse the routing due to conflicts in manuals & various pictures. Left click on the link below to view, or right click and select "save as" to download:

TVR 3000M Cooling System Diagram

John - I tried to reply by email to both addresses but the emails bounced back.

Follow up - contribution by Paul Bennett:

I have attached a diagram of my cooling system which was done by exactly tvr when the previous owner had some work done.

On my cooling system I don't have the pipe from the bleed valve to the water pump marked XXXXXXX or the bypass hose marked oooooooo

I do have the blanking rubber on my water pump.

I also have small hose / pipe which connects from the coolant reservoir tank to the left hand front side of the radiator.

Paul Bennett's Cooling System Diagram

20th June 2005

By Paul Bennett

Do you know if you can get silicone radiator hoses for a 3000m. Not sure about silicone radiator hoses - although Burton Power do a standard set for the 3.0L Capri I think - but you'll need special ones for the radiator hoses and those from the tubular header tank.

23rd May 2005

By Christian Diaz

Hi Mark, been to a british car meeting (about 400 cars) this week end in Bandol : after a 150 miles trip and some trafic jams, the water temp was around 95°/100°. After I stopped the car and let it get cold, I had a look on the engine.

The rad hose was badly compressed on itself : some pressured air escaped from the rad when I opened it... And the hose was looking better immediatly.on the engine.

Would you say the rad cap is in cause (strange, as it brand new), or any air intake somewhere? Any precise parts to look after for an air intake in the water circuit?

In way to help the engine to get more fresh air, would you say it might be more efficient to :

drop off the fan and replace it by a kenlowe unit
add 2 small kenlowes at the front of the rad

Normally the hoses will expand if there is steam/air in the hose due to overheating. Looking back at the photo you sent of your engine a few weeks ago however I can see that the radiator filler cap is a pressure type - when in fact you also have an expansion tank fitted. Therefore the problem is almost certainly the fact you should have a non-pressurised cap fitted to the radiator - only a pressurised cap should be fitted to the expansion tank. Sorry I didn't notice that earlier! See below for explanation to help you:

If you fit a pressure cap to the radiator, the small bypass hose that goes to the expansion bottle will be blocked off by the sprung seal of the cap. A non-pressurised (or sealed) type cap has a simple flat base with a rubber seal - therefore allowing the expanding water to flow freely into the expansion tank. It is the expansion tank which is half full that has the necessary air gap at the top - and it is this which, if the cooling system overheats, will release the pressure.

As you have a pressurised cap on both, the radiator may not retain it's water and eject it into the expansion tank by opening the pressurised radiator cap - the problem is the water cannot return from the expansion tank into the radiator - creating a vacuum - which will explain your collapsed hose!

On no account remove the radiator non-pressurised cap with the engine hot!

As for the fans - I have found 2 small fans to be better than 1 on the low type radiator, although on your radiator a large single fan would be the best.

23rd May

By Paul Bennett

I still have my tvr 3000m in bits !!.

The latest repair is a leaking coreplug (See photo attached) on the drivers side block behind the dipstick.

When I brought the car in January 2005 , I notice a slight weep to the coreplug.

I removed the exhaust manifold and coreplug, Purchased a coreplug set from Burtonpower and tried
to replace coreplug, The coreplug I assume needs a hefty wack to locate in the block.

Problem is there does not seem to be enough space to get a good swing , do you have any ideas
how to get the coreplug installed without removing the engine.

When the coreplug was removed there does seem to be what look like a metal ring which is located in the block and
the coreplug locates within the metal ring (See photo attached) orange sealer is excess from sealer when trying to install coreplug .

As this is my first ford engined classic I don't know if the ring should be removed to reinstall the new core plug.

Do you know what diameter the new coreplug should be.


Follow up on 19th June 2005:

Just to let you know that I had to let my local classic car workshop have a go @ getting the coreplug replaced.

We thought that we would have to take the engine out, But the workshop tried using a hydraulic ram which they fixed to the chassis ,they managed to replace the coreplug ok.

I now have the car back in the garage and am starting on stripping and rebuilding the LH front suspension.

The position of the coreplug is tricky - as you have already found out. The metal ring you mention is (I'm pretty sure) just the way the block has been machined, so don't try to remove it.

Not sure on the diameter, but they are tight to fit anyway and usually need a good belt with a suitable drift (or socket if no drift available) and a lump hammer (carefully!). Engine removal may be your only option if unable to get it in I'm afraid, but you could always try sticking the new plug in the freezer for an hour before trying to fit - sometimes it helps me with tight wheel bearings to freeze the shell first.

Let me know how you get on.











19th May 2005

By Stephen

A question please. I have a 3000S which gives a higher than I think should be temp reading - about 115deg. A physical water check with temp reader gave an actual 10 deg lower than temp gauge. I had the original rad (Capri I think) re-cored and I flushed the system out at that time. I have read yr comments about the voltage stabiliser and will look into this as well. I would like a lower running temp.

I like the sound of fitting a pair of fans behind the rad (and SE turbo vents) but you suggest to keep the original Essex fan as well.

Question: Will I have to modify anything to make room for the electric fans? There would not appear to be sufficient room for the Essex and electric ones.
The temperature being 10º lower using the water temp reader still means it's way too hot. Replacing the voltage stabiliser, or even better changing over to a capillary temp sender/gauge unit is the best method to get the correct temp. reading.

If you have the Capri radiator then that's a taller square one compared to the deep wide one...a single large fan would be better on that type of rad, perhaps making some air ducting in front so the air coming through the bonnet grille is directed better instead of finding its own way through the engine bay.

With your radiator then the Essex engine fan has to come off (I think), although I've never personally worked on one of these. Try "Water Wetter" which is available from Demon Tweeks - that should knock it down about another 5º. However, your temperature is too high and I would seriously check the obvious things first to make sure it's not a corroded water pump impeller or blockage (such as the thermostat jammed, thermostat take off blocked (the small tube behind the thermostat on the inlet manifold), carburettor, steel tube on right hand side of engine from water pump to back of engine. You may get 105º when really hot on a summers day but not healthy for long.

Hope that gives you an idea where to start? Have fun!

17th May 2005

By Christian Diaz

I’m the happy user of a TVR 3000 S (1980 mdel) bought one month ago frome David Gerald. The car h’aven’t been drived for almost the last 4 years, but been serviced and mot’ed before delivery. This is now the –may be- only 3000 s living on the french riviera.

The engine is running well, but overheating. Water temp (on the tudor gauge actually fitted) is commonly about 125° and I blocked the gauge at 140° on the way back from england, in the very heavy traffic of Paris.

Since that time, radiator, thermostat and water pump have been changed for new parts. But the overheat is still here. I noticed on your eexcellent website that the electric gauge might be the cause. I’ll change it for a capillar system from smiths.

But if the trouble persist, what could be the cause?

Is it a good idea to remove the original fan and replace it by a kenlowe unit? Which model could be the most effective? Is an oil radiator needed also?

Follow up reply:

As promised, please find enclosed a pic of my car and some close-ups of the radiator. Sorry, as you can see the engine bay need a good clean, and chassis need a good repaint and rust treatment (any recommendations about that work?).

So, the radiator fitted have been sourced from Nissens automotive radiators of Denmark ( and cost about 250 euros. The model is made for many Ford models, from 69’ to 78’ Capri, and also 71’ Cortina and Escort II. It needed some work to fit in place of the original item, as hoses connexions aren’t exactly symetric. The garage have also cutted (not a proper job as you can see) the “bell” around the fan, which have been cutted too.

would you think a big kenlowe unit might be a good option as replacement of the engine fan? Would I need some Pacet at the front of the rad anyway? And what about an oil rad?

Thanks for your help. I ordered a capillary water gauge from yesterday, and will fit it in place this week end. Hope it will solve that “supposed” overheating trouble. Will keep you informed.

2nd Follow up:

Just to let you know you where right about that supposed overheating on my TVR 3000 s : it wasn’t logical the car could still overheat with a brand new rad, thermostat and waterpump.
Spend Sunday afternoon looking at the engine. Noticed the electric cable between the sender unit on the block and the water gauge was sticked to one of the heater hoses, and touching one of the engine’s heads... Since this cable have been cleaned and unsticked to the hose and not in contact with the head, the gauge says the car now runs very normally : slightly under 90° after a 15 mn ride... And not going upper anymore.

I’ll fit a capillary gauge anyway, but I fill much more better now about my engine!

3rd Follow up:

I’m the french riviera user of a 3000 S which had some heating problems a few weeks ago. I changed the gauge (had a VDO unit, now a smiths with cappilary system), but cannot fit it to the block : the sender sensor is too long and touch inside the block : so I can’t bold it in place!

Europaspares (my smiths dealer) said tthat on any Ford engine, there is a 5/8 bolt udef for draining the water, so I could use this to plug my sender unit in place.

Could you halp me to locate that 5/8 bolt on the essex engine?

Would recommande that solution, or an hose adapter is better way to you?

4th Follow up:

Remember my 3000 s, suffering (well, supposed so) of overheating? You were right, ther gauge was mad! I changed it (a VDO item) for a Smith (cappilary). But I discovered that the sender unit was much too long to be bolted on the block. I ordered for an adaptor from europaspares, which doesn’t work too : it is made for 3,8 cm long senders, mine is about 45 cm!

I finally found the solution by myself : there is an unused hose on the top of my (brand new) water pump (it might be connected to the heater system, as Doug Elwood frome David Gerald told me).

I plugged the sender unit inside the hose and secured it by a metal collar. No water leakage, and... Miracle, I now have a water temp info again!

Yes the overheating problem is a nuisance - definately change the temperature gauge as soon as possibly to the capillary type and you may find it is fine. However, what type of radiator did you fit - is it the low type (under the spare wheel) as if that type and not a larger core type it may well be inadequate.
Also check the electric fan works - you should never really go above 100ºC anyway - 140ºC is dangerously high for the engine. I used a couple of Pacet fans which work quite well - and also try the "water wetter" liquid as I am certain the temperature is now about 5º lower, more in the winter here - mine is running at 80ºC in January with outside air temperature at 10ºC.
Let me know about the radiator so I can help more!

Follow up:

Well any electric fan would be good - Kenlowe are good, yes. I see you have the "tall" type radiator fitted so overheating is supposed to be less of a problem on the cars fitted with these. Wait until you get your new gauge to see if that alters the temperature reading. Just one more idea I have - do you put the spare wheel in place? If so the airflow will be quite restricted through the radiator as the top half is not given a free enough path of air.

Follow up:

Normally the temp. sender is fitted to the inlet manifold as I'm sure you know (in front of the carburettor). The water drain plug on the block is to the rear of the oil filter. The exhaust and starter motor will be quite close to this so I would recommend fitting an adaptor to the original position on the inlet manifold if possible.

Follow up:

Good news - at least now you know that the engine is ok. A good tip about fitting the capillary sender too!

2nd November 2003

by Brian Percival
I have now fitted new heater rad and all new pipe work. Can you advise me on rad caps [ie pressure] for both tanks?
Not sure if the ones on there are the right ones.
The expansion tank cap should be a 13psi type, and the header tower has a non pressure release cap (i.e. it is a total watertight seal) - this is very important! And, never ever open it until the engine is really cool - it'll blast out hot water if you do!

25th March 2003

by Guy Hope

I have acquired a 1976 3000M which has had some modifications fitted to assist air flow. There is an extra electric fan fitted behind the rad. The spare wheel has been removed and an extra aluminium duct fitted to block air flow to the engine and direct it down through the rad. I am not sure if this is effective and by blocking the airflow to the engine may make the problem worse. Should I remove it? Can a better fan be fitted to the engine and can a guard be fitted? Do you have some guidelines/explanations about the cooling system so that I can try and improve things? The car will run up to about 115C and stabilise - should I be concerned about this?

115° is way too hot (but first see note at end of message in bold print). The ducting you mention is supposed to work better but in doing this and blocking airflow over the engine has always been a concern to me - although I know it has been done by a few people.

The standard 3000M radiator with 2x 8" Pacet Fans or Kenlowes will do the trick - the 3000M on my website has 2x Pacets behind the radiator, and has an additive called water wetter (available from Demon Tweaks) which effectively reduces the temp by 5 degrees on this car. I'm assuming you have the standard rad. Also, a thermostat of 82°C or lower if you can get one (try an old style mini thermostat - it's listed as the same type as for the Essex (i have one in the 3000M) and there is one for tropical countries at 78° - also Mini Spares do lower ones for racing.

Always run with a thermostat - without one water flow will be impaired.The standard engine fan improves airflow over the engine in traffic jams - lots of people get rid of it but it definitely slows down the heat build up in my experience. If there isn't one - get one & refit it.
The 3000M is notorious for overheating and my best tip (which I am doing this year) is to cut off the spare wheel mount on the chassis, and fit a standard Ford Cosworth Sierra radiator with one large electric fan - this is said to do the trick and is relatively cheap (I think under £150) - whereas a special alloy 3000M radiator costs around £600 - £800.

To recap - I get 85°C at the current daytime air temp (14°C) at a constant 60mph with standard rad, water wetter additive, 82°C thermostat, 2x 8" Pacet fans fitted behind the rad. with quick fit connectors (these are ok but in time can wear out the radiator core - try to use alloy mounts), a Turbo SE bonnet vent (available from Adrian Venn at Exactly TVR Ltd), standard V6 Essex engine fan. One last mod. I will do apart from the Cosworth rad. is to get a capillary temperature gauge - electric ones can be very innacurate and your high temperature may be a false reading if the voltage stabiliser (again see my website for info on this) is faulty.

Your best money will be spent on a capillary thermostat - buy this first before you do anything!!!